Trypsin inhibitor

Ovomucoid or trypsin inhibitor is an abundant protein in most avian egg whites. The hen′s egg protein is composed of about 186 amino acid residues, and is highly glycosylated. Three tandem domains are each homologous with pancreatic trypsin inhibitor. It is highly immunogenic, and probably accounts for most cases of egg allergy.

25% of ovomucoid comprises carbohydrate.

Trypsin inhibitor from chicken egg white has been used:

• to produce denatured, oxidized and deglycosylated ovomucoid and used to stimulate patient derived cell cultures for mapping T cell epitopes
• to treat nuclei for flow cytometric analysis
• in Holtfreter′s solution, used for the dissociation of planarians into cells

One mg will inhibit 0.8-1.6 mg of tryspin with activity of approx. 10,000 BAEE units per mg protein. May inhibit ≤0.3 mg of chymotrypsin with activity of approx. 40 BTEE units per mg protein.

One trypsin unit will produce a ΔA₂₅₃ of 0.001 per min with BAEE as substrate at pH 7.6 at 25 °C; reaction volume 3.2 mL, 1 cm light path.

Ovomucoid, from chicken egg white, does not itself inhibit chymotrypsin. Chymotrypsin inhibition is a measure of ovoinhibitor contamination by method of Feeney, R. E., et al., J. Biol. Chem., 238, 1415 (1963).

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